上颌骨复合体骨缝牵张的动物实验研究

The experimental study of maxillary protraction through bone suture expansion in animals

目的探索颅颌面骨发育不足治疗新方法,采用骨缝牵张成骨技术刺激猴上颌骨诸骨缝再生,延长面中三分之一。方法实验选用猕猴6只,分为A(4岁)、B(4岁)、C(6岁)、D(8岁)4只,对照组E(5岁)、F(5岁)2只。相当于人类年龄的12．6～22．5岁。对应于人类青少年中后期与成熟期早期。于牵张前3月采用自行研制的前牵引支抗种植体行骨融合种植体植入术。部位为前鼻嵴下方牙槽突内及颧牙槽嵴上各植入两枚种植体。待骨融合后,麻醉状态下安放颅骨坚强外固定架。将NiTi-SMA螺簧连接于支抗种植体与固定架面具之间,进行牵张延长面中三分之一。采用力值为A,B猴500g,C猴800g,D猴1200g。E,F不加力自然生长。牵引方向与(牙合)平面平行。牵张后4、8、10、12周分别取材。进行头颅标本与大体观察；模型测量；X线检查。结果实验组上颌骨均得到不同程度延长。结论不同年龄组实验动物可以通过骨缝牵张诱导缝区大量新骨形成,各缝因受力大小和方向不同而呈现多样性反应,牵张力值较大者形成的新骨多,加大牵引力值可使成年动物达到同样效果：前牵引支抗种植体能够承受实验所加力值。颅骨外固定坚强牵引牵张器具有稳定可靠的牵张作用。

Objective To investigate the possibility of a new approach in maxillary protraction by suture expansion using anchorage implants for correction of midface deficiency and to observe the process of tissue response and regeneration in the circummaxillary suture loaded with tensile orthopedic forces. Methods Six resues aged 4 to 8 years were included, animals A,B, C D tested, animals E, F served as control（did not wear any appliance）. Two osseointegrated titanium protraction anchorge implants were respectively placedin the premaxillary ridge and bilaterally on each side of zgyomaricoalveodar protuberance. When the osseointegrarion of implants had been achieved, extraoral suture expansion appliance was installed and NiTi SMA coil spring was fastened from the framework to the maxillary implants. Distraction began with force of 500g, 800g, and 1200g. Samples were taken after 4,8,10, 12 weeks of distraction and gross inspection, model measure, X- ray examinations and hlstologic observation were performed to observe the changes during the distraction period. Results Gross inspection, model measure and X - ray examination showed that the sutures expansion were completed almost in every animal. The maxillary bone and premaxilla became protrusive significantly at the beginning of the suture expansion, and the suture restored gradually to its original position. At the end of the expansion the length of premaxilla increased by 7mm to 27mm measured in the skull speciment. Conclusion The protraction anchorage implant can bear the forces used in the test .-The external traction appliance used in the study was consistently effective and all the force levels could induce a great amount of new bone formation. The maxilla could be permanently lengthened by anchorage implants suture expansion.